A case of Congential cystic eye in a two month old girl is reported. This rare condition is recognised at birth as a large orbital mass in place of the normal eye. This is perhaps the first reported case with a CT Scan. The CT appearance suggests that the defect in embryogenesis is not confined to the optic vesicle but involves other parts of the brain also.

Congenital cystic eye is a rare ocular malformation Arrest in the invagination of the primary optic vesicle between 2 mm and 7 mm stages of foetal development is considered to be the cause for this But the CT Scan findings in this case suggest that the developmental abnormality is not confined to the arrest of the invagination of the primary optic vesicle.

Case report

A two month old girl,the first child born of non­consanguinous parents presented with a mass in the right eye since birth The mother's pregnancy was uncomplicated and the baby was delivered at full term, normally.

Examination

On examination the baby was found to be well nourished, with normal development There was a fleshy mass in the right eye region 25 x 25 x 10 mms The upper lid appeared ballooned and a reddish pink mass was bulging out [Figure - 1]. The posterior limits of the mass could not be seen The mass was soft and partly cystic in consistency. The mass appeared to be filling the orbit The swelling was not reducible and no cough impulse was present Since the mass filled the orbit the mobility could not be appreciated. Detailed exami­nation under anaesthesia did not reveal any eye ball, cornea or lens The swelling was non­pulsatile The left eye was normal. Rest of the examination was normal.

Investigation

Routine haemogram, urine analysis and bioche­mical tests were normal. Skiagram of the skull showed an enlarged right orbit with a soft mass in it Otherwise the intracranial features were within normal limits [Figure - 2]. A CT Scan was done This revealed a mass in the right orbit which was predominantly hypodense, with a cystic compo­nent anteriorly. Neither the eye ball nor any vestiges of normal orbital contents such as ocular muscles or optic nerve could be seen. The right orbit was larger in size. The left eye appeared normal [Figure - 3]. The lateral ventricles were poorly developed The frontal horn and anterior portion of lateral ventricles were not visualized Well developed occipital and temporal horns on the left side and vestigial right lateral ventricle were seen. There appeared to be an agenesis of the corpus callosum [Figure - 4].

Diagnosis

With the clinical and CT features, a diagnosis of congenital cystic eye with prosencephalic anoma­lies was made.

Treatment

Since there was no useful eye in the righ orbit, but a cystic unsightly mass which protruded between the eye lids, it was decided to remove the orbital contents. The orbit was explored by anterior orbitotomy, preserving the skin of the eye lids The soft and cystic mass was separated from the periorbitalis. No definite ocular muscle tissue could be seen. The mass with its pedicle was excised.

The posterior part of the mass was firm and the anterior part was cystic. The posterior part did not have any communication with the cranial cavity. Even after excising the mass, there was no CSF leak at operation site confirming the lack of communication with the cranial cavity.

Macroscopic examination of the specimen revea­led a 25 x 25 x 10 mms. irregular mass of soft tissue. On cut section the normal structures of the eye such as the retina, choroid, sclera, lens and comea were absent The greyish white soft mass contained a few cystic and slit like spaces.

Microscopically the predominant features were proliferating glial elements. In some areas there was a tendency for the cells to arrange in layers, mimicking the retinal layers A few attempted rosette like formations were also seen. Spaces lined by columnar cells were evident in some places [Figure - 5] a, b, c.

Discussion

Arrest in the invagination of the primary optic vesicle between the 2 mm and 7 mm stages o foetal development is considered to be the cause for a congenital cystic eye, also called anoph thalmos with cyst The term congenital cystic eye ball was given by Ida Mann in 1937 to this rare ocular malformation [5]. Later arrest,between the 7 mm and 14 mm stages produces the more common coloboma.

The CT Scan findings of associated prosencepha lic changes suggest that the developmenta abnormality is not confined to an arrest of the invagination of the primary optic vesicle bu involves other regions of the forebrain.

Although the aetiology of congenital cystic eye i; not known, the frequent presence of inflammatory cells in the cyst suggest an inflammatory cause (Duke Elder 1963 [2].

The ectodermal elements do not differentiate into future cornea and lens The orbit contains, instead of an eye ball, a cyst or multiple cysts, whose anterior wall is made up of more or less identifi­able primitive retinal cells, and the posterior wall by a layer of primitive pigment epithelium The cyst is in general almost completely filled by proliferation of glial tissue.

Clinically congenital cystic eye can be differenti­ated from a colobomatous cyst of the retina, which develops in a globe already formed. The former pushes the upper lid forward, where as the colobomatous cyst of the retina attached to the inferior portion of the globe pushes the lower lid forward.

The cyst maybe single or multiple and may vary in size The size of the cyst is believed by some to be related to the patency of it's stalk If the lumen of the stalk remains open, fluid will not collect and the cyst will remain small If the lumen of the stalk is not patent the cystic eye is large as in the case reported by Helveston et al (1970) [3]. In the case reported by Dollfus et al (1968) [1] the mass was macroscopically not cystic. The present case contained multiple cysts.

A congenital cystic eye may have normal or anomalous extraocular muscles surrounding them and the lids are usually normal In the present case the extraocular muscles had not developed at all.

Microscopically congenital cystic eye is described as being made up of disorganised neuroecto­dermal elements that may have differentiated sufficiently to display primitive retinal and cho­roidal structures Glial proliferation is common and angiomatous vascular net works may be present (Hogen & Zimmerman 1966) [4].

Conclusion

A case of congenital cystic eye in a two month old girl is reported. This is the first case report with a CT Scan. The presence of prosencephalic abnormalities suggest that the defect in develop­ment is not confined to the optic vesicle.